The present invention relates to a GPS (Global Positioning System, worldwide positioning system) device for receiving waves from a GPS satellite and measuring the position of the receiver and the moving speed. More particularly, the present invention relates to a wrist watch type GPS device which may be maintained and mounted on the a wrist of a human being for measuring his or her position and moving direction.
Conventionally, in a GPS receiver, as shown in FIG. 6, a GPS wave 61 emitted from a GPS satellite is received in the GPS receiver 62, the signal is processed at a high speed in a GPS received signal processing means 63 such as a frequency calculator, an orbit information calculator section or the like, and, as a result, the obtained measured data is displayed on a GPS data display means 64. If it is considered that such a GPS receiver is worn on the wrist, a receiving posture or position of an antenna becomes a problem. A conventional technology to keep the posture of the antenna in a constant position is shown in FIG. 7. In the prior art shown in FIG. 7, an antenna portion 71 and an operating section 72 may be integrally connected to each other by a support member 74 having a wave receiving surface 73 of the antenna portion 71 supported rotatably within a predetermined angle relative to a horizontal surface H, and, at the same time, the gravity position of the antenna portion 71 may be measured downwardly in the vertical direction below the rotational center of the gravity position of the antenna portion 71. Also, a weight (balancer) 75 is provided below the antenna portion 71, so that the antenna portion 71 is normally kept in the horizontal direction to thereby keep the antenna position where the wave may normally be received. Such a conventional example is shown in Japanese Patent Laid-Open Application No. Hei 4-359179.
In general, in view of the fact that the angle of elevation of the antenna at which a signal may be received is 15 device or more relative to the horizontal surface, the position of the antenna when the wrist watch type GPS receiver is realized becomes a serious problem. In the case where the GPS antenna is arranged on the surface that is flush with the display means of the GPS receiver, when the GPS receiver is portable with the wrist in a natural posture, the GPS receiver takes an antenna posture in which the GPS receiving is impossible. The fact that the normal signal receiving operation is performed in such an antenna posture where the wave cannot definitely be received increases the power consumption rate. In particular, a high speed calculation process is required in the GPS received signal processing means of the GPS receiver, and an orbit calculating device having a very high speed processing ability is also required, resulting in an increase in power consumption. The fact that the operation of the GPS received signal processing means is continued for the antenna posture in which the wave cannot definitely be received leads to a large loss. On the other hand, there has been proposed a method for keeping the antenna posture in a constant position when the GPS signal is received. However, in order to keep the posture in a constant position, it is very difficult to use the device.